The present invention relates to .Iadd.the application .Iaddend.of a solar control film to .[.be applied to.]. windows in order to reduce transmission therethrough of infrared, visible and ultraviolet radiation from the sun. Reduction of infrared transmission limits interior heating in the summer and interior cooling in the winter. Reduction of visible light transmission limits uncomfortable glare. And reduction of ultraviolet transmission limits fabric fading and finish cracking of furniture. Solar control film is intended to reflect solar infrared and ultraviolet and still to permit excellent visibility with minimum distortion. It has been found that 100 square feet of such film as a comparative cooling capacity equal to more than one ton of air conditioning. In effect this film is a two way thermal insulation that is partially transparent. Difficulties have been encountered in storing such films compactly and in laminating and maintaining such films in superposition on windows.
A typical prior solar control film comprises a polymeric sheet, a vapor deposited aluminum coat, a protective polymeric coat, and a pressure sensitive coat, which is deactivated initially by the presence of an agent that eliminates tack during storage, as well as during the time the film is being applied to a window. Just before the film is applied to the window, the pressure sensitive adhesive coating is subjected to water, in consequence of which the agent is dissolved and the pressure sensitive adhesive is reactivated to produce a final bond when dry. .[.When moistening the pressure sensitive adhesive, the water is intended to wash away all of the water soluble agent. But, this washing step is never complete so that some agent always remains. In consequence, the bond between the film and the window can be ruptured when ambient moisture permeates into the interface between the film and the window. Another.]. .Iadd.A .Iaddend.drawback of this structure is that the protective polymeric coat tends to crack, ripple and rupture whereby deterioration of the aluminum coat occurs and optical clarity is harmed.
The primary object of the present invention is to provide a .Iadd.process for applying a solar control film to a window, the .Iaddend.solar control film comprising a vapor deposited aluminum coat, which is of a thickness characterized by a light transmission of 5 to 50 percent, interposed between a pair of moisture permeable polymeric strata, each of which ranges in thickness from 1/4 to 1 mil so as to be individually self supporting.Iadd., there being an internal bonding stratum between the polymeric strata and an external pressure sensitive stratum at an outer surface of one of the polymeric strata. .Iaddend.It has been found that the self supporting strata eliminate physical and chemical degradation that typically occurs at the vapor deposited aluminum coat in prior systems. .Iadd.It is believed that the pressure sensitive stratum retains its bonding strength and predetermined thickness because it is not reactivated by ambient humidity, moisture or water and conforms to microscopic and macroscopic lumps and cracks in the glass substrate and the polymeric strata so as to provide an intimate bond without adversely affecting optical clarity. .Iaddend.In one modification of the solar control film, an optional integral outer coat on one of the polymeric strata is composed of a pressure sensitive adhesive in association with a discrete silicone release sheet. In another modification, an .[.optional.]. .Iadd.optical .Iaddend.integral outer coat on the other of the polymeric strata is composed of a silicone release agent. In such modifications, storage in roll form is permitted by the incompatbility of the pressure sensitive adhesive and the silicone release agent, application to the window glass is enabled by a water compatible de-tackifier which is applied to the pressure sensitive adhesive, and permanent implacement is achieved by permeation of the water compatible de-tackifier through the film and via the edges.
Other objects of the present invention will in part be obvious and will in part appear hereinafter.
The invention accordingly comprises the products and processes, together with their components, steps and interrelationships, which are exemplified in the accompanying disclosure, the scope of which will be indicated in the appended claims.